Clean up aligned allocation code in preparation for SIMD alignments.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index f460b55960d58e1fd08e91c651c413bd31b8b848..8bce634fd0e03b63e1a674b23500344331618cb2 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -716,13 +716,10 @@ class Heap {
   MUST_USE_RESULT AllocationResult
       CopyJSObject(JSObject* source, AllocationSite* site = NULL);
 
-  // This method assumes overallocation of one word. It will store a filler
-  // before the object if the given object is not double aligned, otherwise
-  // it will place the filler after the object.
-  MUST_USE_RESULT HeapObject* EnsureAligned(HeapObject* object, int size,
-                                            AllocationAlignment alignment);
+  static int GetAlignmentSize(Address address, AllocationAlignment alignment);
 
-  MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object);
+  MUST_USE_RESULT HeapObject* PrecedeWithFiller(HeapObject* object,
+                                                int fill_size);
 
   // Clear the Instanceof cache (used when a prototype changes).
   inline void ClearInstanceofCache();